I finally got round to putting my original system board with discrete AMD Radeon HD 6470M w/1GB back in to my EliteBook 8560p, what a pain, had to do it three times, first time no sound, and second time no bluetooth / WLAN. Eventually once the hardware was sorted upgraded the HD3000 Yosemite confirguration using USB boot, press F4 at Clover screen and boot to HDD, took forever to get to a logon screen and then an age to get to the desktop, we are talking hours not minutes. Applied all the relevant settings using PBI 6.2.15 RC2 and re-booted with fingers crossed!

All working except sound, so used Kext Wizard to repair permissions and rebuild cache, and following a further re-boot all working well, including switching to headphones output when connected. Overall performance and especially graphics performance appears improved over the HD 3000 configuration. Also I can now pass graphics through the HP Standard and Advanced Base Station(s) rather than having to use the Display Port on the back of the laptop, and best of all I have support for three monitors, although resolution and graphics quality is currently poor for the VGA port.

Finally my existing installation of Windows 10 Enterprise x64 (EFI) running on the same HDD still works fine, just had to add my OS X partition as the Default Boot Volume in the Boot settings in config.plist using Clover Configurator.

Thanks to all for the hard work in providing the tools to get OS X Yosemite running so well on my HP EliteBook 8560p.